Contamination of organic compounds by carbonyl compounds, especially aldehydes, is a particular problem in the manufacture and utilization of humectants, food additives, and preservatives (e.g., glycerine, 1,3-propanediol, and 1,3-butanediol) and also in the manufacture of fiber or plastics monomers such as bis-(hydroxyethyl) terephthalate. Where use of the material in foods, pharmaceuticals, cosmetics, etc. is contemplated, very small quantities of carbonyl contaminants are undesirable in that they frequently impart an objectionable taste or odor to the end product. Likewise, in the production of high polymers such as those employed in fiber manufacture, very small quantities of carbonyl contaminants cause an undesirable off color in the polymer and, even more important in most cases, act as so-called "chain stoppers" which prevent the formation of the desired long polymer chains.
The problem of carbonyl contamination in products of the types just discussed has been dealt with heretofore by methods which, with varying degrees of effectiveness, have included steam stripping (which usually entails the use of high vacuum and high steam consumption), solvent extraction (which is often not effective in removing the last traces of contamination which are still sufficient to cause problems), and chemical treatment such as the formation of bisulfite addition products (which frequently entails relatively complicated processing and which can itself introduce quality problems unless careful control methods are employed).
Thus, there remains a need for a carbonyl-removal method which is simple, effective, and economical.
It is, accordingly, an object of the present invention to provide a straightforward method for removing a carbonyl compound from a liquid containing said carbonyl compound as a solute. More particularly it is an object to provide a method for purifying an organic compound which is contaminated with an aldehyde or a ketone, especially an aldehyde. Other objects of the invention will be apparent from the following detailed description.